rs12948217, also known as c.693C>A, Y231X or Tyr231Ter, is a SNP in the ASPA gene. Note that a benign variant of this SNP (c.693C>T) also exists as discussed below.

Only the A allele at rs12948217 confers risk to Canavan disease. A person with the CC, CT, or TT alleles is not a carrier; someone with the AC or AT alleles is a carrier; and people with two AA alleles are affected with the disease.

Note that due for technical reasons, the vast majority of direct-to-consumer companies using DNA chips (microarrays) for genotyping do not distinguish the benign T allele from the pathogenic A allele. As a result, raw data from these companies that reports (A;C) and especially (A;A) is quite likely to actually represent the benign (C;T) or perhaps (T;T) genotypes. This type of error applies only to data derived from microarrays (specifically, Illumina microarrays such as those used by 23andMe and Ancestry) and does not apply to data generated by sequencing.